Trojan:W32/DNSChanger will change the infected system's Domain Name Server (DNS) settings in order to divert traffic to unsolicited, and potentially illegal sites.
Based on the settings of your F-Secure security product, it will either move the file to the quarantine where it cannot spread or cause harm, or remove it.
A False Positive is when a file is incorrectly detected as harmful, usually because its code or behavior resembles known harmful programs. A False Positive will usually be fixed in a subsequent database update without any action needed on your part. If you wish, you may also:
Check for the latest database updates
First check if your F-Secure security program is using the latest detection database updates, then try scanning the file again.
Submit a sample
After checking, if you still believe the file is incorrectly detected, you can submit a sample of it for re-analysis.
NOTE If the file was moved to quarantine, you need to collect the file from quarantine before you can submit it.
Exclude a file from further scanning
If you are certain that the file is safe and want to continue using it, you can exclude it from further scanning by the F-Secure security product.
Note You need administrative rights to change the settings.
Trojan:W32/DNSChanger is a family of malware used by an organized crime syndicate to perpetuate click-fraud, where user's browsing activity is quietly manipulated (such as redirecting a user who clicks on a legitimate link to an unsolicited site) so that the attackers can generate revenue from pay-per-click online advertising schemes.
The trojan is usually a small file (about 1.5 kilobytes) that is designed to change the 'NameServer' Registry key value to a custom IP address. This IP address is usually encrypted in the body of a trojan.
As a result of this change, a victim's computer will contact the newly assigned DNS server to resolve names of different webservers.
This malware is discussed further in the following Labs Weblog post:
Lately we got a few samples of this trojan that were named 'PayPal-2.5.200-MSWin32-x86-2005.exe'. This trojan was programmed to change the DNS server name of a victim's computer to 22.214.171.124 address.
The Registry key that is affected by this trojan is:
Other registry modifications made involve creating these keys: